Stays can be used to hold a casement window in open or closed positions, while fasteners are used to keep the window securely shut. There are three main types of casement window fasteners: hook, wedge and mortise fasteners.
Stays are the long bars that fit to the opening casement of a window. They typically have numerous holes that can be pinned to allow the window to be secured in different positions. If the stay does not have a setting that can hold the window closed, then a fastener is also needed.
The type of fastener needed depends on how the window closes against the frame. A hook fastener works with windows that close flush with the frame. Wedge or mortise fasteners are for windows that close against the frame.